Theophylact of Ohrid

But to say "come down from the cross" — the devil was prompting them to this. Since the prince of evil knew that salvation would be accomplished by the cross, he again tempted the Lord, so that if He descended from the cross, it would be confirmed that He was not the Son of God, and thus the salvation of mankind through the cross would be destroyed. But He was the true Son of God, and for this very reason He did not come down from the cross. …

Commentary on Mark ↗

Augustine of Hippo

How can this be, when according to Luke one only reviled Him, but was rebuked by the other who believed on God; unless we understand that Matthew and Mark, who touched but slightly on this place, put the plural for the singular number?

Catena Aurea by Aquinas ↗

Bede

And those who were crucified with Him were also insulting Him. How were those who were crucified with Him insulting Him, when indeed one of them insulted Him, according to the testimony of Luke, the other rebuked him and believed in God? Unless we understand that Matthew and Mark, summarizing briefly, used the plural number for the singular in this place, as we read it is said in the plural in the Epistle to the Hebrews: They shut the mouths of lions (Heb. 11), when it is understood to mean Daniel alone. …

On the Gospel of Mark ↗